Technical Abstract:
Direct demonstration of tospovirus gene function has been impeded by the absence of reliable reverse genetics systems for this virus genus. Use of a Tobacco mosaic virus (TMV)-based expression system has demonstrated that the Tomato spotted wilt virus (TSWV) NSm protein supports cell-to-cell movement in the absence of other TSWV proteins. Essential TSWV NSm domains required for tubule formation, movement and symptoms were identified previously by deletion-mapping and alanine-substitution mutagenesis using the TMV-based system. Our mutagenesis studies of TSWV NSm amino acids that are conserved in other tospovirus NSm proteins suggest that functional domains may be conserved across the genus, especially for species in the ‘New World’ group. To that end, we initiated studies of the Impatiens necrotic spot virus (INSV) NSm protein using similar TMV-based mutagenesis approaches and we report here new insights into the tospovirus NSm protein based on our functional analysis of the INSV NSm protein.